Health Canada adds mercury limits for 6 fish
Changing eating habits have led Health Canada to establish new mercury limits on six species of fish.
The fish — fresh and frozen tuna, shark, swordfish, escolar, marlin and orange roughy — are predators thattend to have higher levels of mercury because of their relative size, lifespan and diet, the department said.
The mercury limit for the fish, which were previously exempt from standards, is1.0 parts per million (ppm).
The reportnotes the lower availability ofthese fishcompared with canned tuna, but Canadians are eating more of them, Dr. Samuel Godefroy, director of the bureau of chemical safety in Health Canada's food directorate, told the Canadian Press.
"Sushi bars are more common in Canada now than they used to be in the past," he said.
But even so, for three of the fish— escolar (snake mackerel), marlin and orange roughy— the department said the volumes Canadians eat are negligible.
For the other three, only tuna appears to be a big favourite with consumers. About 40,000 tonnes of tuna were imported or caught in 2004, compared with 4,500 tonnes of shark (mostly dogfish) and 266 tonnes of swordfish.
By comparison, about 148,000 tonnes of shrimp was landed or imported.
Fish still provide good nutrition
The department is still stressing the nutritional benefits of eating fish. Canada's Food Guide recommends eatingat least two 75-gram servings offish each week.
For the six fishunder the new standard,"the general population can eat up to 150 grams per week," it said.
However, women who are or may become pregnant and breastfeeding mothers should cut that to 150 grams a month. Young children between 5 and 11 should limit their consumption to125 grams amonth, and younger children should not exceed75 grams a month.
4 species over new guideline
The department's report said that four species exceeded the new guideline in at least one sample.
"Marlin, shark, swordfish, and fresh tuna were each reported at least once to contain total mercury at average levels greater than1.0 ppm," the report said.
According to tables included with the report, most samples are under the new limit. For example, none of the two batches (15 fish)of orange roughy tested at more than 0.47 ppm.
But for marlin, three of six batches (25 out of 170 fish) tested over1.0 ppm.
At least one sample each of shark, marlin and swordfish was far over the new limit. The top shark sample was 1.62 ppm, swordfish hit 1.82 ppm and marlin was 1.43 ppm.
The report said that the new limit was set for the six fish because eachhadtotal mercury of about half the limit, or0.5 ppm.
The department said the standardfor other fish, including canned tuna, will remain at 0.5 ppm.
Health Canada said thechanges follow a major review that looked at themost recent scientific information about fish consumption and mercury.
"It is the most comprehensive national assessment on mercury in fish done to date," the department said.